How to Deep Clean a Sand Filter (And Change Sand)

So, perhaps it’s been a year or two and you’re thinking about either deep cleaning your sand filter or changing the sand entirely. To help you with that, I’ll be showing you the main ways of doing so, which products to use, as well as answering some other questions that’ll hopefully help you along the way.

Deep cleaning your sand filter is relatively easy as it only requires a sand filter cleaner and some manipulation of your pool pump. If you’re thinking about changing your pool filter sand instead, you should empty your filter tank to replace the old sand with new sand.

First, let’s take a look at deep cleaning and how it works, before moving on to changing the sand. Sand changes usually only need to take place once every 3 to 5 years.

multiport valve sand filter
multiport valve sand filter

Deep Cleaning a Sand Filter

Why Deep Clean a Sand Filter?

Deep cleaning is used to completely cleanse your filter by removing any particles that a typical backwash can’t remove. Unlike backwashing, deep cleaning uses chemicals to remove all debris from your sand filter, instead of just reversing the flow to push the debris out.

Therefore, you’ll only have to deep clean when debris clogs up your filter despite you having already backwashed.

When Do You Need to Deep Clean?

You typically only need to deep clean once every year or so. If you find, after backwashing, that the filter pressure hasn’t lowered substantially or your water remains a little cloudy, deep cleaning the sand filter might be the answer.

Of course, if you haven’t been backwashing regularly, which removes the majority of the debris, you’ll have to deep clean more often.

As a guide, when your filter’s pressure gauge is showing 8 to 10 PSI higher than usual, that’s an indication that your filter needs cleaning.

How to Deep Clean a Sand Filter

What You Will Need

Backwash Hose

Milliard 50 ft Heavy Duty Backwash Hose, Great for Water Disposal - Weather and Chemical Resistant - 2 inch Diameter

Filter Cleaner

NamePriceProsCons
HTH 67025 Filter Cleaner Care for Swimming Pools, 1 qtUnder $50Compatible with all pool filters (i.e. cartridges, D.E., and sand)

Compatible with all pool types including salt pools
Not as effective for larger filters (i.e. inner and outer type cartridges)

Not as effective at times for certain filter types
GLB Pool & Spa Products 71006 2-Pound Pool Water Filter CleanerUnder $50Compatible with all filter types

Compatible with all sanitation types
Not as long-lasting as some of the other products, thus it’s recommended to be used monthly

Relatively expensive for the amount

HTH 67025 Filter Cleaner Care for Swimming Pools, 1 qt

HTH 67025 Filter Cleaner Care for Swimming Pools, 1 qt

GLB Pool & Spa Products 71006 2-Pound Pool Water Filter Cleaner

GLB Pool & Spa Products 71006 2-Pound Pool Water Filter Cleaner

Deep cleaning a sand filter, though may sound like an extensive process, is much simpler than you may think. Here is the main gist of the steps you’ll have to follow:

1. Prepare to Backwash

Connect your backwash hose, turn off the pump, and set the valve to “backwash”.

2. Backwash the Filter

Turn on the pump and backwash for 3-5 minutes. When done, turn off the pump and set the value to “filter”. Refer to our article How to Backwash a Pool Filter & How Often for the steps.

backwash setting
backwash setting

3. With the Pump Switched Off, Pour in the Filter Cleaner

Open the pump lid and pour the sand filter cleaner into the pump’s strainer basket. Dosage will depend on the specific product.

4. Turn the Pump on for 15 Seconds

Switch the pump on for 15 seconds before turning it back off. This moves the cleaner from the pump to the filter tank.

5. Leave for 8+ Hours

Let the cleaner sit and do its work in the tank for at least 8 hours.

6. Backwash the Filter Again

Set the valve to “backwash” and turn the pump on for 3 to 5 minutes to remove whatever debris the cleaner dislodged. Turn the pump off and set the valve to “rinse”.  Turn the pump back on for 15 seconds to rinse out the tank. Turn the pump off and set the valve to “filter”.

This step will clean out the filter and remove all the gunk and the filter cleaner from the system.

7. Filter the Water as Normal

Finally, turn the pump back on and let your pool system run as normal. Make sure to check that the filter’s PSI is back to its normal level

As you can see, besides the sand filter cleaner, there’s nothing else to add to deep clean your sand filter. All in all, it’s a relatively simple process, if you don’t mind all the turning on and off.

filter setting
filter setting

Changing/Topping Up the Sand

Now that we’ve taken an in-depth look at deep cleaning your sand filter, let’s see what you’ll need to do if the sand itself has gotten too worn out. If that’s the case, your best option will be to change the sand in your sand filter entirely.

Why Would You Need to Change the Sand?

You should only change the sand in your sand filter if the sand itself is no longer filtering out debris from the water. Unlike when you need to deep clean your sand filter due to debris clogging the sand, the issue here is that the sand itself is becoming smoothed out over time due to the amount of water passing through. Once the sand loses its rough texture, it loses its ability to filter dirt, bugs, and other organic matter.

Therefore, you can’t just clean the sand here, instead, you’ll have to replace it entirely.

How to Change and Top Up Sand

In short, you’ll need to switch off your pool equipment, open up your pool filter and scoop all the sand out. When this is done, you can refill it.

We have an in-depth article on the process here: When to Change the Sand in the Pool Filter (And the Risks)

Filter Sand
Filter Sand

Related Reading: How Much Sand to Put in a Sand Filter (How Far to Fill)

Changing Sand Vs Deep Cleaning

As we’ve discussed, both changing and deep cleaning the sand is done when your sand filter is no longer functioning properly. They’re two different ways of keeping your sand filter running properly by maintaining the efficacy of the sand.

The difference here is the specific issue these methods tackle. Changing the sand is required when the sand itself is no longer able to trap debris due to changes in its structure (similar to the weathering of rocks), while deep cleaning is required when too much debris has clogged the sand.

Since it usually takes a significant amount of time for the sand to smooth out, it makes sense that you’ll only have to replace it once every 3 years at the earliest (sometimes it can last up to 7 years).

Final Thoughts

There’s quite a bit of information we’ve gone over today, but the main point is to help you clean or replace the sand in your sand filter for it to work properly. Regardless of your situation, I hope this article will serve as a helpful guide for you. With just a few simple steps and (possibly) a few dollars, I’m sure you’ll have your filter (and pool) back up and running in no time.

Related Reading: How to Choose the Best Pool Pump for an Intex Pool

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